Hardware Manual. Crumb128. Rapid Prototyping Module with the Atmega128 AVR Microcontroller

Transcription

1 Hardware Manual Crumb128 Rapid Prototyping Module with the Atmega128 AVR Microcontroller

2 Version 1.1 Copyright 2004 Dr. Erik Lins, Development and Distribution of Hardware and Software. All right reserved. Dr. Erik Lins makes no warranty for the use of its products and assumes no responsibility for any errors which may appear in this document nor does it make a commitment to update the information contained herein. Dr. Erik Lins products are not intended for use in medical, life saving or life sustaining applications. Dr. Erik Lins retains the right to make changes to these specifications at any time, without notice. All product names referenced herein are trademarks of their respective companies.

3 Contents 1 About the Crumb128 Module 1 Features 1 2 Functional Description 2 Digital Power Supply 2 Analog Power Supply 2 System Reset 2 System Clock 3 Serial Port 3 LED Indicator 4 In-System-Programming Port 4 Expansion Port Connectors 5 Memories 6 Fuse Bits 6 3 Testing the Board 7 Starting the Bootloader 7 Starting the Monitor Program 7 Working with the Monitor Program 8 Electrical Characteristics 10 4 Part List 11 5 Schematics 12 6 Board Layout 13 7 Links 14 8 Firmware Copyright Notice 15 Obtaining the Sourcecode 15

4 1 About the Crumb128 Module 1 About the Crumb128 Module Low-cost rapid prototyping module with the ATmega128 AVR controller. Crumb128 is a low-cost and easy to use rapid prototyping module combining Atmels ATmega128 AVR microcontroller with a small set of peripheral components on a tiny pluggable board. Thus it is well suited for tasks like: learning the AVR architecture rapid prototyping without need of surface mount technology breadbording and test of applications building block in embedded (scalable) applications Features The Crumb128 module provides the following components: small size of 40x30mm² ATmega128-16AI microcontroller in the TQFP64 package reset protection circuitry for the ATmega128 two pin reset connector status LED standard 6-pin In-System-Programming (ISP) connector standard serial port on 5-pin connector with RS232 transmitter / receiver all ATmega128 signals available on two 32pin connectors A preinstalled firmware (stk500mon) provides a SKT500 compatible bootloader, hence no ISP adapter is required to download software into the ATmega128. You just need a serial crossover cable to connect the Crumb128's serial port to a PC running the programming software (e.g. AVR-Studio, uisp, avrdude, etc.). The stk500mon can also be used for low level hardware tests of the ATmega128 microcontroller and peripheral circuits. 1

5 2 Functional Description 2 Functional Description This chapter explains the main functions of the Crumb128 module. Digital Power Supply Crumb128 requires a +5V DC regulated power supply, which needs to be applied to the two VCC pins of the expansion connectors. See expansion port connector description for pinout. The two VCC pins are connected internally, hence for testing the board (e.g. download software through In-System Programming port or serial port) it is sufficient to connect only one VCC pin. During normal operation the +5V power supply should be connected to both VCC pins on the expansion connectors! Analog Power Supply The analog VCC pin AVCC of the ATmega128 is connected internally to VCC through coil L1 and decoupled by ceramic capacitor C5, hence it should not be connected externally to VCC. Furthermore AVCC can be used to power an external analog circuitry, if the analog-to-digital converters of the ATmega128 are being used. If a high quality analog power supply is available anyway and should be used to power the AVCC pin of the ATmega128, coil L1 has to be removed! System Reset The reset input signal of the ATmega128 is generated by charging a 47nF capacitor (C11) through a 4.7kOhm resistor (R7) at +5V. The 4148 type silicon diode D3 ensures a quick discharge of the capacitor if the power supply is switched off. By closing jumper J1 a manual reset can be triggered. 2

6 2 Functional Description System Clock The ATmega128 microcontroller clock (XTAL) is generated by a MHz crystal (X1), other crystal frequencies are available on request (up to 16MHz). An additional kHz quarz (X2) drives an on-chip asynchronous timer (TOSC), which is typically used for a software realtime clock. Note, that changing the MHz crystal will affect the baudrates of the serial port used by the preinstalled firmware application! Serial Port Crumb128 provides an onboard 5pin connector for it's RS232 serial communications port. This port is connected to the first USART port of the ATmega128 via a single chip RS232 transmitter/receiver interface circuit MAX221 (U2), which converts the TTL logic signals to RS232 signals and vice versa. The RS232 transmitter/receiver device can be enabled/disabled by setting jumper J2. See picture on the right for details. The following table shows the available signals of the 5pin serial port connector. Pins Signal Function NC RXD TXD NC GND Not connected Receive Data Transmit Data Not connected Signal ground The pin assignment is identical to the upper row (pins 1,3,5,7,9) of a standard male DB-9 connector in DTE configuration, hence a DB-9 connector can be connected 1:1. See picture on the right. 3

7 2 Functional Description LED Indicator One LED indicator is available on the Crumb128 module. LED1 is connected to pin 17 (OC2 OC1C PB7) of the ATmega128 and can be used as a status indicator of the application software The preinstalled chip45mon bootloader and test firmware flashes LED1 three times after reset going inactive. In-System-Programming Port Never plug in the programming adapter while power is supplied to the PROBOmega128 board. You may damage the PROBOmega128 board or the parallel/serial port of your PC! This port allows serial (re-)programming of the ATmega128 nonvolatile Flash-ROM and EEPROM memories, without the need to remove the microcontroller from the system. The programming signals (PE0 and PE1) are used as serial port signals during normal operation, hence resistors between the ATmega128 and the RS232 interface circuit protect the programming adapter against the receiver output of the interface circuit. During programming random data may appear at the DB-9 connector TXD signal. During normal operation of the serial port the ISP adapter has to be removed from the ISP connector! Care must be taken, when using these signals in own applications, never directly connect output signals when using the ISP port! Pins Signal Function MISO VTG SCK MOSI /RST GND Programming data output (from AVR) Target Voltage (supplies the adapter) Programming data clock (to AVR) Programming data input (to AVR) Reset signal Ground 4

8 2 Functional Description Expansion Port Connectors All ATmega128 systems signals are available on two standard 2.54mm pitch pin headers. CON1 This expansion connector provides the ATmega128 signals 1 to 32. Pins Signal Function / / NC PE0..7 PB0..7 NC /RESET VCC GND NC PD0..7 Not connected internally 8 bit bidirectional digital Port E 8 bit bidirectional digital Port B Not connected internally Low active reset signal +5V power supply Signal ground Not connected internally 8 bit bidirectional digital Port D Note: Counting starts from top to bottom! CON2 This expansion connector provides the ATmega128 signal 33 to 64. Pins Signal Function PG0 /WR PG1 /RD PC0..7 PG2 ALE PA7..0 VCC GND PF7..0 AREF GND AVCC Digital port signal PG0 or /WR Digital port signal PG1 or /RD 8 bit bidirectional digital Port C Digital port signal PG2 or ALE 8 bit bidirectional digital Port A +5V power supply Signal ground 8 bit Port F or analog inputs ADC0..7 Analog reference voltage Signal ground Analog power supply Note: Counting starts from bottom to top! 5

9 2 Functional Description Memories The ATmega128 microcontroller provides 128 kbytes of on-chip, nonvolatile flash memory, which is used for program code and read-only data storage. It is organized as 64k x 16 bit and can be (re-) programmed through the in-system programming port. 4 kbytes of ATmega128 on-chip SRAM can be used for read/write data storage. Up to 64 kbytes of SRAM can be added externally. The ATmega128 provides additional 4 kbytes of on-chip, non-volatile, electrically erasable memory (EEPROM), which is typically used for storage of configuration data. This memory is accessible under software control as well as through the in-system programming port. Note, that write access to the EEPROM memory is much slower (typically about 2.5msec) than writing to the SRAM! Fuse Bits The fuse bits of the ATmega128 microcontroller are preprogrammed to fit the external oscillator and the preinstalled stk500mon bootloader. The following table shows the values of the three fuse bytes: Fuse Byte Value Comment Extended 0xFF ATmega103 compatibility mode disabled High 0xC8 JTAG disabled, CKOPT programmed, boot size of 8kbyte, boot reset vector Low 0x3F Brown out detection enabled, BOD level 4.0V, 65ms startup time, high freq oscillator Note, that it is not possible to re-programm the fuse bits or lock bits with the preinstalled STK500 bootloader firmware!!! For reprogramming the fuse bits an ISP adapter is required! 6

10 3 Testing the Board 3 Testing the Board Using the preloaded firmware to test the Crumb128 hardware. The Crumb128 module comes with a preinstalled bootloader and test firmware (stk500mon), which allows either quick and basic tests of the hardware as well as STK500 compatible in-system programming of the ATmega128 through the serial port. The most recent version of the stk500mon bootloader and test firmware can be downloaded as source code and precompiled hex file at Note that an ISP programming adapter is required to update the firmware through the ISP connector, it is not possible to use the STK500 bootloader to overwrite itself! Starting the Bootloader 1. Connect Crumb128's serial port to an available COM port using a serial crossover (RXD and TXD crossover connection) cable. Hardware handshaking is not used by stk500mon, hence a three wire cable (RXD, TXD and signal ground) is sufficient for operation. 2. Pull PF7 ADC7 TDI pin of ATmega128 low. This can be done by placing a jumper/ball of solder across pins 21 and 22 of expansion port connector CON2. See picture on the right. 3. Reset the Crumb128 board by either switching the power off/on or by setting/unsetting jumper J1. 4. If the bootloader is entered successfully, the onboard LED flashes three times and then remains off. 5. Start your STK500 compatible programming software on the PC. 6. The PC software should recognize an STK500 compatible target. Starting the Monitor Program 1. Connect Crumb128's serial port to an available COM port using a serial crossover (RXD and TXD crossover connection) cable. 7

11 3 Testing the Board Hardware handshaking is not used by stk500mon, hence a three wire cable (RXD, TXD and signal ground) is sufficient for operation. 2. Start your favorate terminal emulation software on the PC (e.g. TeraTermPro on Windows or minicom on Linux) and set the baudrate to baud, 8 data bits, no parity and 1 stop bit. Disable hardware (RTS/CTS) and software (XON/XOFF) flow control. 3. Pull PF7 ADC7 TDI pin of ATmega128 low. This can be done by placing a jumper/ball of solder across pins 21 and 22 of expansion port connector CON2. See picture above. 4. Reset the Crumb128 module by either switching the power off/on or by setting/unsetting jumper J1. 5. If the bootloader is entered successfully, the onboard LED flashes three times and then remains off. 6. Enter '!' (exclamation mark) three times at your terminal emulation program and wait until the stk500mon welcome message is displayed. 7. If the monitor program is entered successfully, the onboard LED is turned on. The stk500mon monitor program is now ready to receive commands. Working with the Monitor Program Always check the most recent version of stk500mon as well as the most recent version of the Crumb128 Hardware Manual for latest features at Pressing '!' (exclamation mark) three times on a terminal emulation program after resetting the board with PF7 pulled low enables the stk500mon monitor program and the following welcome message will be displayed: 8

12 3 Testing the Board stk500mon (C) Jason P. Kyle See for details. Enter commands: r aaaa : read byte w aaaa bb: write byte t : toggle led b : external bus loop u : uart0 echo The next line shows a colon, which is the command prompt. Command Overview The following table gives a short description of the monitor commands. Command r aaaa w aaaa bb t b u Description The byte at hexadecimal address 'aaaa' is read and displayed. The hexadecimal byte 'bb' is written to hexadecimal address 'aaaa'. Toggle onboard LED, the current status is displayed (ON/OFF) The external bus of the ATmega128 is enabled and the CPU reads from addresses 0x1100 up to 0xffff (external I/O memory space) in an endless loop. The board has to be reset to end this command. In an endless loop any byte, which is received through the serial port is echoed. The board has to be reset to end this command. The commands 'r' and 'w' perform memory mapped I/O accesses, hence when reading status registers (SFR), the memory mapped address has to be entered. See pages 24 (I/O Memory) and 354 to 356 (Register Summary) of the ATmega128 data sheet! Note, that it is not possible to re-programm the fuse bits or lock bits with the preinstalled STK500 bootloader firmware!!! For reprogramming the fuse bits an ISP adapter is required! 9

13 3 Testing the Board Electrical Characteristics This chapter provides basic electrical characteristics of Crumb128. For electrical characteristics and absolute maximum ratings of ATmega128 I/O pins as well as timing diagrams of peripheral interface signals please refer to the most recent version of the ATmega128 data sheet (see Chapter 8 Links). Parameter Value Operating Temperature -20 C to 70 C Operating Voltage +5V ±10% Operating Current (RS232 enabled, no connection to host) Operating Current (RS232 enabled, connection to host) Operating Current (RS232 disabled) 28.5mA typ. 36.0mA typ. 28.2mA typ. 10

14 4 Part List 4 Part List Designator Part Type Description C1 22p Ceramic capacitor C2 22p Ceramic capacitor C3 100n Ceramic capacitor C4 100n Ceramic capacitor C5 100n Ceramic capacitor C6 47n Ceramic capacitor C7 100n Ceramic capacitor C8 100n Ceramic capacitor C9 100n Ceramic capacitor C10 100n Ceramic capacitor C11 100n Ceramic capacitor CON1 IDC32 Pin header, 2 x 16pin, 2.54mm spacing CON2 IDC32 Pin header, 2 x 16pin, 2.54mm spacing CON3 IDC6 AVR ISP Connector, 6pin, 2.54mm spacing CON4 RS232 Pin header, 1 x 5pin, 2.54mm spacing D1 1N4148 Small signal diode 1N4148 J1 RESET Jumper, 2pin, module reset J2 RS232 Enable Solder jumper, 3pin, RS232 enable/disable L1 10uH SMT coil, 0805 LED1 LED SMT LED, green, 0805 R1 4.7kOhm Resistor, 0603, 1% R2 1.5kOhm Resistor, 0603, 1% R6 4.7kOhm Resistor, 0603, 1% R7 4.7kOhm Resistor, 0603, 1% R8 4.7kOhm Resistor, 0603, 1% U1 ATmega128-16AI ATmega128-16AI AVR microcontroller U2 MAX221EUE 1T/1R RS232 transmitter/receiver circuit X MHz XTAL SMT clock crystal, Epson, FA365 X kHz TOSC SMT clock crystal, Epson, MC146 11

15 5 Schematics 5 Schematics 12

16 6 Board Layout 6 Board Layout 13

17 7 Links 7 Links This chapter contains useful links to related documentation. The official Atmel AVR homepage with data sheets, application notes, software, etc. Direct link to the ATmega128 product page The ATmega128 data sheet AVRFreaks.net provides extensive information on AVR controllers, software examples, assembler, the free AVR-GCC compiler and tools, own application notes and tutorials, forums, companies, etc. Learning the AVR assembler language with practical examples, PDF version for download available, forum Portal site for embedded systems, avr related information page 14

18 8 Firmware Copyright Notice 8 Firmware Copyright Notice Copyright notice and reference to the GNU General Public License. The stk500mon firmware is copyright 2003/2004, Jason P Kyle. Monitor and debug functions were added by Dr. Erik Lins. The stk500mon firmware is free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA USA Licence can be viewed at Obtaining the Sourcecode The full sourcecode and makefile of stk500mon is available at The original stk500boot sourcecode and makefile is available at 15

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20 Dr. Erik Lins Distribution and Development of Hardware and Software Am Pfad 8 D Linden Germany Fon +49 (0) Fax +49 (0) info@lins.de